Al-Qaida terrorists and Niger rebels pose an "immense challenge" to oil companies who want to press ahead with a $20bn project to build a pipeline through the Sahara desert to bring new gas supplies from west Africa to Europe, analysts warn.

The ambitious scheme was considered a fanciful dream until Total of France gave its verbal backing to the project, seen as a way of bringing gas from Nigeria to lessen Europe's dependence on Russia. Global Insight, a financial and political consultant, believes the scheme is still fraught with danger. Samuel Ciszuk, Middle East analyst at the firm, said: "Niger's Tuareg rebels or al-Qaida in the Maghreb pose formidable obstacles in the vast, sparsely populated expanse."

The national oil companies of Nigeria and Algeria originally proposed building the Trans-Sahara Gas Pipeline, but Total is the first western oil major to voice support - and give it credibility.